1. Field of the Invention
This invention relates generally to pumps for viscous fluids. Specifically, the invention is a hand pump for use with condiments such as flavored syrups, catsup, mustard, mayonnaise, relish and similar products.
2. Description of Related Art.
Nearly all retail stores which sell ready to eat food have some type of system for allowing the customer to apply various condiments (e.g. catsup, mustard, relish, flavored syrup, etc.) to the food. And while there are various approaches to the problem of storing and dispensing condiments, one popular approach is to use a stainless steel tub and hand pump.
In general, the prior art consists of a piston displacement pump, an inlet chamber with a check valve, an outlet chamber with a check valve, and a dispensing spout. The combination of a piston displacement pump with two chambers and check valves predates their use in food dispensing. For example, Berdahl used this arrangement in an oil can, U.S. Pat. No. 1,307,478, granted Jun. 24, 1919. Turning to food dispensing, Cox used the same basic elements in an adjustable syrup pump, U.S. Pat. No. 3,332,585, as did Bennett et al. in U.S. Pat. No. 5,579,959. Two recent, popular food pumps, using this same approach, are Schaefer et al., U.S. Pat. No. 5,375,746, and Humphrey, U.S. Pat. No. 5,381,932.
A review of the prior art patents, particularly the discussion in Schaefer et al, Humphrey, and Bennett et al., shows that there has been an ongoing sense of frustration with the prior art pumps on the following grounds: they are too complicated to manufacture; they have too many parts; they are prone to clogging; and, they are difficult to clean.
Accordingly, there is a need for a condiment pump which is easy to manufacture, has a minimum of parts, resists dogging, and is easy to clean.